The present invention relates to an improved client apparatus and server apparatus applicable to a system which supplies desired content, such as music content, to interested users via a communication network, and an improved communication method for supplying desired content, such as music content, to interested users via a communication network.
In recent years, delivering various digital content, such as music content and image content, via the Internet or other communication network has become very popular. Any interested user can purchase or acquire music or other desired content by connecting his or her personal computer or communication terminal, such as a portable phone (e.g., cellular phone), to a communication network and downloading the desired content from an information provider (server) that supplies a multiplicity of music and/or other content. Japanese Patent Application Laid-open Publication Nos. HEI-10-275186 and 2001-42866 corresponding to U.S. Pat. No. 6,570,080, etc. disclose a content supply system, which allows sample or trial content to be supplied to an interested user so that the user can decide on purchasing desired content after having actually reproduced the supplied trial content, e.g. after having test-listened to the trial content if the supplied trial content is music content. The “trial content” is, for example, content providing only a part of a music piece data set, or content having limited reproducibility, such as a limited reproducible time length. Heretofore, it has been conventional for a server to transmit trial content in response to a trial use request from a client apparatus and then transmit separate purchasing content (i.e., regular content to be purchased) in response to completion of a predetermined content purchase procedure performed by the user of the client apparatus.
The conventionally-known technique, where sample or trial content and purchasing content is transmitted separately, would present poor usability because there is a need for a user to perform content downloading twice in order to acquire desired purchasing content. Particularly, where the user's computer is incapable of high-speed data transfer, it would take a very long time to acquire the desired content, which tends to greatly degrade convenience of the content supply service.
If same content is used both as trial content and as purchasing content as was the case with the traditional technique, then downloading the content only once would suffice. In many of such cases, an information provider gives a predetermined serial number to each person who has completed a predetermined content purchase procedure, so that, unless the serial number is entered by a requesting person, the provider only allows the content to be reproduced as trial content with limited reproducibility; only when the serial number has been entered by the requesting person, the provider allows the requested content to be reproduced normally with no reproducibility limitation. However, in case the requesting person copies both the supplied content and serial number, the provider can not appropriately prevent the supplied content from being used limitlessly. Thus, this technique could not provide sufficient security against unfair use of the supplied content.